Transcript Predicting Domestic Homicide

Does prior history of domestic violence predict
domestic murder or other serious assaults?
Sara Thornton, Thames Valley Police
The claim
• There is a clear relationship between
everyday…interpersonal violence…and…domestic
homicide (Websdale 1994)
• There is therefore an opportunity to intervene in
escalating patterns of violence
• Therefore we need to assess the risk based on
predictors drawn from studies of domestic murders
• Prediction can lead to prevention
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The research questions
• In how many cases was there a prior history of
reported domestic violence?
• How accurate were the risk assessments based on
prior history in terms of false positives and false
negatives?
• Might a prospective denominator-based prediction
produce more accurate forecasting than a
numerator-based prediction?
• Are the predictors for murder different from other
serious assaults?
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DASH high risk factors for
potential murder victims
•
•
•
•
•
•
•
•
•
Fear
Isolation
Separation
Conflict over a child
Stalking
Pregnancy
Child abuse
Frequency of abuse
Escalation of abuse
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•
•
•
•
•
•
•
•
•
Jealousy
Weapons
Threats to kill
Strangulation
Sexual assault
Other threats
Mistreat animals
Drug abuse
Attempt suicide
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Domestic Violence Offences
Offence
Murder
Attempt
murder
Manslaughter
GBH with
intent
Total
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3 Years - Numbers 2007 to
2009
% of
sample
13
11
16
14
1
1
88
74
118
100
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Gender and outcomes
Murder
Attempt
murder
GBH with
All
Manslaughter
intent offences
Female
victims
11
15
(85%) (94%)
40
1 (45%)
67
Male
victims
2
(15%)
1
(6%)
48
0 (55%)
51
13
16
Total
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1
88
118
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Risk of death per attack:
4 times higher for women victims
Female Victims
Male Victims
Attacks = 67
Attacks = 51
Death
= 11
Deaths = 2
Ratio
= 1 in 6
Ratio
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= 1 in 25
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Victim prior contact with the police
Victim has prior recorded domestic
incident contact with police since
1/1/2000
Number
%
YES
53
44.9
NO
65
55.1
118
100
Total
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Prior risk assessment
Risk assessment for victim on
most recent prior domestic
incident (n=53)
Number
%
Valid %
5
4.2
9.4
Medium
21
17.8
39.6
Standard
21
17.8
39.6
Prior contact but risk assessment
not known or not recorded
6
5.1
11.3
N/A as no prior domestic incident
contact with police
65
55.1
-
118
100
100
High
Total
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How well did DASH predict?
• None of the 13 murder victims had been assessed
as high risk
• Of the 6 murder victims who had been risk
assessed following a previous incident, 1 was
assessed as medium risk and 5 standard risk
• No prior domestic incident contact with police for 7
of the murder victims
• DASH missed 55% of attacks
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Prior domestic incident contacts between
victim & police
Total number of contacts
Number of
victims
Cumulative
%
20+
3
2
10-19
5
7
2-9
20
24
1
25
45
Sub total contacts
53
45
No prior Domestic Incident
contact with police
65
55
Total
118
100
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Most recent prior victim contact with the
police for domestic incidents (n=53)
Nature of victim's most recent prior
domestic incident contact with the
police
Number
%
Non-crime domestic incident
16
30.2
Actual Bodily Harm
16
30.2
Assault without injury
7
13.2
Criminal Damage
4
7.5
Threats to kill
4
7.5
Harassment
3
5.7
Racist incident non-recordable crime
1
1.9
GBH with intent
1
1.9
Arson with intent to endanger life
1
1.9
53
100
Total
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Offender criminal record
Previous criminal record
Number % of sample
Suspect has prior criminal
record
87
73.7
[Suspect has prior criminal
record for a violent offence]
70
59.3
Suspect has no prior criminal
record
27
22.8
4
3.4
118
100
No record traced/missing data
Total
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Next steps
• Collect data on the false positives: analyse
MARAC watch list
• Investigate potential denominators
• Identify further studies which have
assessed the effectiveness of DASH or its
predecessor
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Thank you